2.7 Chemical and biological health hazards and risk control

Question 1

What forms of chemical agents can be found?

Answer 1

Sometimes these chemicals can be
found already in the workplace – for example, cleaning agents or raw materials – or be generated by processes, dusts and fumes. A chemical substance that is not harmful in a specific form can be very harmful in another, as this will dictate how the substance enters and affects the body.

Question 2

Name and define the 2 types that chemicals can be separated into?

Answer 2

• A substance is a chemical element or a compound, including any impurities.
• A preparation is a mixture of substances, often with a deliberately proportioned
composition.

Question 3

List the forms that chemicals, substances and preparations can be found in?

Answer 3

• Liquids – chemicals that are normally at a temperature between freezing (solid) and
boiling (vapours and gases
• Gases – any substance at a temperature above its boiling point. Steam is the gaseous form of water.
• Solids – materials that are solid at normal temperature and pressure.
• Vapours – substances that are close to boiling point in a gaseous form.
• Fibres – dusts with a length to width ratio of more than 3:1. This includes asbestos.
• Mists – similar to vapours
• Aerosol – fine suspension of solid particles or droplets in a carrier gas.
• Smoke – particles that result from incomplete combustion
• Dusts – solid particles that are heavier than air but can be suspended in it for a limited period of time.
Fumes – a collection of very small metallic particles (less than 1μm, which are respirable particles) that have condensed from the gaseous state

Question 4

Name the forms of biological agents?

Answer 4

• Fungi and moulds – very small organisms that live as parasites on living animals or
plants. They feed from organic matter and reproduce by producing spores, which can
cause an allergic reaction. An example is Aspergillosis, or farmer’s lung
• Bacteria – very small single-celled organisms which can live in or outside of the body, and smaller than human cells.
e.g. legionella and zoonoses
• Viruses – live inside the body and use host cells to reproduce. They are the smallest known type of infectious agent, and cannot be controlled by drugs.
e.g. Hepatitus and AIDS

Question 5

What are suppliers of dangerous chemicals required to do?

Answer 5

• identify the hazards (dangers) of the chemical. This is known as ‘classification’;
• give information about the hazards to their customers. Suppliers usually provide this information on the package itself (e.g. a label); and
• package the chemical safely

Question 6

What are the most common chemical classifications?

Answer 6

• Irritant – a non-corrosive substance or preparation which through prolonged or repeated contact with the skin or mucous membrane can cause inflammation, abdominal pain
• Sensitising – may cause an allergic skin or respiratory reaction, which will worsen on
further exposure (allergic dermatitis or allergic asthma).
• Harmful – those substances or preparations that, if swallowed, inhaled or absorbed by the skin, may pose limited health risks.
• Corrosive – these substances will affect the area by burning living tissue. They are
usually strong acids or alkali.
• Toxic – substances or preparations classified in this group will prevent the correct functioning of one or more organs within the body, such as kidneys
• Carcinogenic – substances and preparations which, if inhaled, ingested or absorbed by the skin, may induce cancer or increase its incidence

Question 7

Define acute and chronic health effects?

Answer 7

Acute health effects appear very quickly after exposure, maybe within seconds, minutes or hours depending on the chemical. Normally these symptoms disappear as quickly as they came once exposure is terminated, there is quick and obvious evidence of exposure – for example, burns with corrosive substances are more easily controlled with adequate equipment and personal protective equipment.

Chronic health effects occur after long-term exposure, where substances have time to be absorbed by the body. In these scenarios symptoms may take months or
years to appear. Chronic health effects are difficult to prevent as most of the time people do not detect exposure until it is very late. Sometimes symptoms are confused with day-to-day illnesses, and once it is diagnosed the illness is too
advanced where it will require lengthy medical treatment, or it may be impossible to fully recover, finally causing an early death.

Question 8

What are the different routes a hazardous substance may enter the body?

Answer 8

Inhalation
This is the most common route found in industry, where the agent becomes airborne and is breathed in together with air through the nose or mouth and absorbed through the lungs passing to the blood stream, where it is then carried to the organs or attacks directly the lung tissue, causing a local effect.

Ingestion
The hazardous substance or preparation enters the body through the mouth and it is
swallowed all the way through the digestive tract to the stomach and intestines. It is unlikely that by accident significant quantities of harmful chemicals will enter the body.

Absorption
The substance or preparation is absorbed through the skin, eyes or through an open wound. The substance may cause a local effect such as burns, dermatitis or cracking of the horny layer, or pass through the membranes of the eye and skin and be capable of entering the
blood stream, accumulating in the body and causing organ failure.

Injection
The substance or preparation is forced through the skin, for example by accidental contact with a syringe, broken glass or an animal bite that will carry a hazardous substance through the skin layer.

Question 9

What does the ILO Code of Practice require competent authority to do in safe use of chemicals?

Answer 9

To ensure that criteria are established on measures which provide for safety of workers, in particular:
• in the production and handling of hazardous chemicals;
• in the storage of hazardous chemicals;
• in the transport of hazardous chemicals, consistent with national or international
transport regulations; and
• in the disposal and treatment of hazardous chemicals and hazardous waste products, consistent with national or international regulations.

Question 10

What factors should be considered whenassessing the risk to safety and health?

Answer 10

• the form of the substance – solid, liquid, dust, gas, etc.;
• the dangerous classification: toxic, very toxic, corrosive, etc.;
• how much of the substance is going to be used;
• how often the substance is going to be used;
• the most likely route of entrance to the body – inhalation, ingestion, absorption or
injection;
• acute and chronic effects caused by exposure;
• natural defences of the body to accidental exposure;
• symptoms presented after short- and long-term exposure;
• vulnerable people; and
• existing control measures

Question 11

What are the general responsibilities of employers in regards to chemical safety?

Answer 11

• Employers should set out in writing their policy and arrangements on safety in the use of chemicals. This information should be brought to the attention of their workers in a language they readily understand.
• Employers should ensure that all chemicals used at work are labelled or marked in accordance with the provisions of the Code of Practice, and that chemical safety data sheets have been provided in respect of all hazardous chemicals used at work.
• Employers receiving chemicals that have not been labelled or marked, or provided with chemical safety data sheets in accordance with the provisions of the Code should not use the chemicals until the relevant information has been obtained.
• Employers should maintain a record of hazardous chemicals used at the workplace, cross-referenced to the appropriate chemical safety data sheets
• Employers should make an assessment of the risks arising from the use of chemicals at work, taking into account the information provided by the supplier
• Employers should take appropriate measures to protect workers against the risks identified by the assessment of risks.
• Employers should comply with appropriate standards, codes and guidelines formulated
• Employers should ensure adequate and competent supervision of work and work
practices
• Employers should make adequate arrangements to deal with incidents and accidents involving chemicals, e.g. accidental exposure, inadvertent release
• Employers should provide their workers with necessary, appropriate and periodic
instructions and training

Question 12

What are the 4 types of occupational exposure limits (OEL)?

Answer 12

• Time-weighted average (TWA) – the maximum average concentration of a chemical in air for a normal eight-hour working day and 40-hour week.
• Short-term exposure limit (STEL) – the maximum average concentration to which
workers can be exposed for a short period (usually 15 minutes).
• Ceiling value – the concentration that should not be exceeeded at any time.
• Maximum permissible concentrations or threshold limit values (TLVs).

Question 13

Where can important sources of information on chemicals be obtained?

Answer 13

Product labels
All substances classified as dangerous that are available to be used in the workplace must be labelled.
Material Safety Data Sheets (MSDS)

Question 14

What information do MSDS contain?

Answer 14

• Identification, name and description of the substance or preparation;
• Name and address of manufacturer or supplier, including an emergency contact;
• Hazards identification, dangerous classification if available;
• Composition and information on ingredients;
• First aid measures;
• Firefighting measures;
• Accidental release measures;
• Handling and storage requirements;
• Exposure controls and personal protection required;
• Physical and chemical properties of the substance or preparation;
• Stability and reactivity;
• Toxicological information;
• Ecological information;
• Disposal considerations;
• Transport information;
• Regulatory information; and
• Other information.

Question 15

What are the limitations in assessing the risk to health?

Answer 15

The information available in the material safety datasheets, labels and EH40 is very
technical and will require expertise in order to understand and apply the information in a
substance assessment. Sometimes the information available does not directly apply to the work activities assessed. Reliance on the data available only is not advisable, and a complete assessment must be carried out where other factors such as the individual, the environment,
and the type of activity are also taken into consideration.

Question 16

What equipment can be used for substance monitoring?

Answer 16

Stain tube detectors
These are sampling devices used for measuring contaminated air. However, manufacturers claim an inaccuracy of 20%, making them inaccurate, although they are a good, quick and easy way
of detecting contamination in the air

Passive sampling
This is measured continuously over a full working day. Normally the worker will wear a badge with some absorbent material that
will absorb the contaminant gas or vapour without the use of a pump.

Sampling pumps and heads
These can be used to measure gases and dusts. There are two types of samplers; they can be static where they are located in a specific area of the workplace, or they can be personal.

Dust monitoring equipment
These are instruments used to observe the effect of dust in the air that is not visible to
the naked eye. A Tyndall Lamp uses a strong beam of light; this method does not give a numerical reading but provides good information regarding the efficiency of local exhaust ventilation.

Question 17

Define long term and short term exposure limits?

Answer 17

• LTEL (long-term exposure limit) – the WEL averaged over a period of eight hours TWA, which is used to help protect against chronic ill health effects.
• STEL (short-term exposure limit) – the WEL measured over a period of 15 minute TWA, which is used to protect from acute ill health effects such as eye or skin irritation.

Question 18

What control measures need to be observed in chemical safety?

Answer 18

Duty to prevent exposure
Employers must ensure that exposure of their employees to substances hazardous to health
is either prevented or, where this is not reasonably practicable, adequately controlled.

Ensuring OELs are not exceeded
Where it is not reasonably practicable to prevent exposure, and in order to ensure that occupational exposure limits are not exceeded, there is a legal duty to implement adequate control measures.
• Design and use appropriate work processes, systems and engineering controls and use suitable work equipment and materials.
• Control the exposure of the substance at source (e.g. enclosures, adequate exhaust
ventilation systems and appropriate organisational measures).
• Where adequate control cannot be achieved by other means, provide adequate
protective equipment (such as suitable chemical protective gloves).

Principles of good practice

Question 19

List the principles of good practice?

Answer 19

Principle 1: Design and operate processes and activities to minimise emission, release and spread of substances hazardous to health
Principle 2: Take into account all relevant routes of exposure (inhalation, skin and ingestion) when developing control measures
Principle 3: Control exposure by measures that are proportionate to the health risk
Principle 4: Choose the most effective and reliable control options that minimise the escape and spread of substances hazardous to health taking into account ergonomics and ease of use
Principle 5: Where adequate control of exposure cannot be achieved by other means, provide, in combination with other control measures, suitable personal protective equipment
Principle 6: Check and review all control measures for their continuing effectiveness
Principle 7: Inform or train employees on the hazards and risks from substances with which they work, and the use of control measures developed to minimise the risks
Principle 8: Ensure that the introduction of measures to control exposure does not increase the overall risk to health and safety

Question 20

What is the hierarchy of control for chemicals?

Answer 20

Elimination
Substitution
Provision of engineering controls
Provision of supervisory (people) controls
Provision of personal protective equipment

Question 21

Name the 3 types of asbestos?

Answer 21

There are three types of asbestos – crocidolite (blue), amosite (brown) and chrysotile (white). The blue and brown are considered to be the most dangerous

Question 22

List some specific chemical agents?

Answer 22

Asbestos
Silica
Cement
Wood dust
Ammonia
Chlorine
Organic solvents
Carbon dioxide
Carbon monoxide
Isocyanates
Lead
Hepatitus
Legionella
Leptospira

Question 23

What are the 3 main areas of pollution?

Answer 23

Land pollution
This is mainly caused by solid waste deposited in land, e.g. landfill or
industrial spillages. Environment pollution mainly affects land, with 60% of controlled waste going into landfill.

Water pollution
Water is present in the planet in all three phases – solid, liquid and vapour. Most water vapour is present in the atmosphere,
liquid water in the rivers and oceans, and solid in the form of ice. Water is most affected by pollution in its liquid state, and occurs when liquid or solid waste manages to enter water routes, through rivers, sewages or drains

Air pollution
Air or atmospheric pollution mainly occurs when fumes, smoke or dust are allowed to enter the atmosphere through chimneys,
incinerators or local exhaust ventilation.

Question 24

How can company’s prevent emmissions to the environment?

Answer 24

• redesigning processes to eliminate the use, generation or release of hazardous
substances;
• utilising ‘clean technology’, e.g. replacing solvent cleaning with an ultrasonic process;
• ensuring storage tanks are adequately bunded to contain leaks and releases;
• introducing effective spillage procedures;
• implementing interceptors, traps, sumps, etc. to prevent the release of oils and fuels to drainage systems;
• ensuring maintenance and inspection of equipment; and
• establishing effective management procedures, including monitoring and review.

Question 25

Define waste?

Answer 25

Waste is defined as any substance or object the holder discards, intends to discard, or is required to discard. This can be scrap material, effluent or unwanted substances, something that is broken or worn out, something contaminated or spoilt, or something discarded.

Question 26

How can waste be classified?

Answer 26

• Controlled waste – defined as household, industrial and commercial waste or any
substance that is scrap, effluent or unwanted surplus from a process.
• Hazardous waste – defined as waste that may be so dangerous or difficult to treat, keep or dispose of that special provision is required for dealing with it.
• Non-hazardous waste – refers to materials that are not covered by the above
description of hazardous waste and includes household waste, paper, wood and other biodegradable materials.

Question 27

List some practical ways to minimise waste?

Answer 27

• reducing the amount of raw
material and energy involved in
processes;
• reusing materials and recovering
energy;
• recycling materials;
• converting waste into energy, e.g.
incineration; and
• disposing to landfill or land raising